The previous mayor, Boris Johnson, championed the project after it was devised by Joanna Lumley, and later backed by George Osborne and former Richmond Park MP Zac Goldsmith.

Osborne and Johnson committed £60m of public money to the bridge, hoping to raise the remaining costs from corporate donations but continued opposition from neighbours and a housing association meant construction was constantly postponed and costs soared.

As planning permission for the bridge expires December the original timetable appeared impossible, Mr Khan said, and while the project was not officially scrapped, the withdrawal of public funds effectively means the end of the project.

Labour MP Margaret Hodge, who was commissioned by Mr Khan to investigate the cost-effectiveness of the project, suggested in a damning report, published earlier this month, that the project be scrapped completely.

“I believe it is better for the taxpayer to accept the loss than to risk the additional demands if the project proceeds. In the present climate, with continuing pressures on public spending, it is difficult to justify further public investment in the garden bridge,” the report said.

The estimated £60m bridge would cost more than £200m, with £37.4m of public money already spent with no construction to show for it, according to the report.

Ms Hodge also found that Garden Bridge Trust had secured only £69m in private pledges, the last of which came in August 2016, leaving a £71m gap.

Mr Khan said this money had already been spent before land agreements talks had closed.